Automatic shutdown device for pumping units



Sept. 13, 1966 J. A. QUEEN AUTOMATIC SHUTDOWN DEVICE FOR PUMPING UNITS 5 Sheets-Sheet 1 Original Filed Nov. 5, 1962 INVENTOR JOHN A. Our-5N mm J. A. QUEEN AUTOMATIC SHUTDOWN DEVICE FOR PUMPING UNITS Sept. 13, 1966 5 Sheets-Sheet 2 Original Filed Nov. 5, 1962 INVENTOR. L/oH/v "4a QUEE-A/ flTTOQ/VE) //0 VOL r5 AC.

Ti E4 Fig-3 Sept. 13, 1966 J. A. QUEEN AUTOMATIC SHUTDOWN DEVICE FOR PUMPING UNITS Z5 $heets-Sheet 5 Original Filed Nov. 5, 1962 INVENTOR. /OHA/ A QUE/5M ZYQZZA A TITS/2N9? United States Patent 3,272,937 AUTOMATIC SHUTDOWN DEVICE FOR PUMPING UNITS John A. Queen, Hobbs, N. Mex, assignor to Continental Oil Company, .Ponca City, Okla, a corporation of Delaware Original application Nov. 5, 1962, Ser. No. 235,325, new Patent No. 3,211,848, dated Oct. 12, 1965. Divided and this application Mar. 29, 1965, Ser. No. 443,411

4 Claims. (Cl. 20081) This is a divisional application of the co-pending application of the present inventor, entitled, Automatic Shutdown Device for Pumping Units, Serial No. 235,325, tiled November 5, 1962, now Patent No. 3,211,848.

The present invention relates to automatic control devices for disabling pumping units as a result of a malfunction and more particularly, but not by way of limitation, relates to a device for automatically disabling an oil well pumping unit when the stuffing box begins to leak excessively.

In recent years, a concerted effort toward the more efiicient utilization of labor has resulted in almost total automation of oil field production equipment. As a result of this automation and corresponding reduction in manpower, the lease overseer, who is known as the pumper, may be able to inspect each pumping unit only once every several days or perhaps only once each week. Therefore, it becomes vitally important that the pumping unit be automatically stopped in the event of a malfunction which would cause damage to either equipment or the lessors property if the pump continues to operate. To this end, many devices have been proposed, some of which have been highly successful, for shutting down a pumping unit as a consequence of various specific malfunctions. For example, inertia-type switches have been adapted to cause immediate shutdown whenever the walking beam of the unit has departed from a predetermined pattern or standard, such as may happen when a sucker rod parts. Shutdown devices responsive to socalled fluid pound are also known and have been adapted to shut down pumping units when the subsurface pump has lost suction. Shutdown devices responsive to a decrease in the sag of the rodline have also been used so as to disable the pumping unit when the well becomes pumped off. Shutdown devices responsive generally to a decrease in the pump rate have also been proposed.

However, no shutdown devices have heretofore been available to shut down operation of a unit in direct response to leakage of the stuffing box disposed at the top of the tubing string which provides the fluid seal around the reciprocating polished rod. As is well known by those who Work in the oil field, when the resilient packing material in the stufiing box begins to leak, the escaping crude oil is forced through the leak under high pressure during each production stroke of the pump. If not quickly corrected, a minor leak will quickly worsen until a large volume of the crude oil is sprayed into the air during each stroke of the pump. 'In addition to wasting valuable crude oil, the spraying oil is a very serious fire hazard, will usually kill all vegetation with which it comes in contact, will usually permanently destroy the soil insofar as plant life is concerned, and is frequently deadly poison to prize cattle, which for some reason tend to regard the oil as a delightful treat. Further, the escaping crude oil has a tendency to pollute streams and spread the hazard to cattle and other animals. Consequently, in the event a stufling box fails on an unattended lease, it is imperative that the pumping unit be shut down so as to relieve the pressure and prevent further escape of the crude oil.

3,272,937 Patented Sept. 13, 1966 Therefore, although it will be evident to those skilled in the art that the present invention is applicable to many other analogous situations, it is a primary object of the present invention to provide a device for automatically shutting down an oil field pumping unit when the stufling box which serves as a packing gland between the reciprocating polished rod and the tubing string in which the polished rod is reciprocated begins to leak excessively. In general, the device constructed in accordance with the present invention comprises a baffle disposed at least partially above the stutfing box so that crude oil sprayed therefrom will contact the bafile, switch means connected to the bafile for actuation in the presence of crude oil contacting the baflie, and circuit means connected to the switch and to the pumping unit for disabling the pumping unit upon actuation of the switch. In accordance with one embodiment of the present invention, the bafile includes a receptacle for collecting fluid deflected by the bafile, and the switch means is actuated by the collection of fluid to thereby disable the pumping unit. In accordance with another embodiment of the present invention, the switch means is responsive to impact by the sprayed crude oil to disable the pumping unit. Additional novel details of the several embodiments of the present invention are more particularly pointed out in the appended claims which, it will be understood, constitute the sole limitations upon the scope of the present invention.

Therefore, it is an important object of the present invention to provide a device for reliably disabling a pumping unit as a result of failure of the stuffing box.

Another object of the present invention is to provide an automatic shutdown device of the type described which will not be triggered by rain or other adverse weather conditions.

Still another object of the present invention is to provide an automatic shutdown device which may be quickly and easily installed around the polished rod while the polished rod is connected to the horses head of the walking beam.

Still another object of the present invention is to provide a shutdown relatively simple,

Many additional objects and advantages of the present invention will be evident to those skilled in the art from the following detailed description and drawings, wherein:

FIGURE 1 is a vertical sectional view of a shutdown device constructed in accordance with the present invention;

FIGURE 2 is a top view of the device of FIGURE 1;

FIGURE 3 is a partial side view of the shutdown device of FIGURE 1;

FIGURE 4 is a schematic diagram of the electrical circuitry of the shutdown device of FIGURE 1;

FIGURE 5 is a vertical sectional view of another shutdown device constructed in accordance with the present invention;

FIGURE 6 is a top view of the shutdown device of FIGURE 5;

FIGURE 7 is a sectional view taken substantially on lines 77 of FIGURE 1; and,

FIGURE 8 is a partial vertical sectional view of still another shutdown device constructed in accordance with the present invention.

Referring now to the drawings, and in particular to FIGURE 1, the upper end of the casing string of an oil well is schematically represented at 10. A tubing string 12 is disposed within the casing string 10 and is closed by a conventional casing head member, indicated by the reference numeral 14. The tubing string 12 may have a pumping T 16 through which production fluid will flow. A polished rod 18 is connected to and forms a part of the rod string which extends from the horses head of the walking beam downwarly through the tubing string 12 to the subsurface pump. A stuffing box assembly, shown schematically and referenced by the numeral 20, includes a suitable resilient packing material which provides a fluid tight joint between the upper end of the tubing string 12 and the polished rod 18. When the polished rod and attached rod string are reciprocated by the pumping unit, the subsurface pump will pump fluid upwardly through the tubing string and outwardly through the pumping T 16. Although the pumped fluid will not be at what would generally be considered a high pressure, the fluid will exert considerable pressure during each production stroke of the pump on the resilient packing material 22 within the stuffing box 20. Accordingly, after varying periods of service, the resilient packing rings frequently become worn and permit oil to pass between the packing material and the polished rod and spray upwardly with considerable force to a substantial height during each upstroke of the polished rod 18.

A shutdown device constructed in accordance with the present invention is indicated generally by the reference numeral 25 and comprises a bafile member 26 which is disposed above the stuffing box 20 and around the polished rod 18. The bafl le member 26 is preferably formed of two semicircular half discs 28 and 30 having curved, radial cross sections, substantially as shown in the sectional view of FIGURE 1, and general outline, as shown in the plan view of FIGURE 2. Referring to FIGURE 2, it will be noted that the disc half 28 extends clockwise from the edge 28a, shown in dotted line, around to the edge 28b which overlaps the edge 30a of the disc half 30, also shown in dotted outline. Similarly, the disc half 30 extends counterclockwise from the edge 30a around to the edge 30b, which overlaps the edge 28a of the disc half 28. Thus it will be noted that the two disc halves 28 and 30 are of identical construction.

The edge 28b which overlaps the edge 30a is illustrated in FIGURE 3 wherein it will be noted that the tab portion 34 of the disc half 28 is raised slightly along the radial line 36 such that the major portions of the disc halve-s 28 and 30 may be aligned. Two or more screws 38 may then be threaded through the tab portion 34 into the disc half 30 to secure the two disc halves together. A similar tab portion 40 (see FIGURE 2) is provided on the other end of the disc half 30 and overlaps the edge 38a of the disc half 28. Screws 42 pass through the tab 40 into the disc half 28 to secure the other end-s of the two disc halves 28 and 30 together and thereby form the integral, circular baffle member 26 which is disposed around the polished rod 18. The innermost edges of the disc halves 28 and 30 preferably are provided with arcuate downturned portions 44 and 46, respectively, which tend to deflect fluid outwardly and into receptacles presently to be described. This construction also provides a small well for receiving a resilient, split sealing ring 48 which may be held in position by two arcuate retainer plates 50 and 52 which are fastened to the tops of the disc halves 28 and 30 by suitable screws.

Horizontally disposed, arcuate flange portions 54 and 56 extend around the outer peripheries of the disc halves 28 and 30. A pair of crescent-shaped fluid receptacles 60 and 62, each having a radial cross section substantially as shown in FIGURE 1, are connected by mating,

arcuate flange portions 64 and 66 on the receptacles 60 and 62, respectively, to the flange portions 54 and 56 of the disc halves 28 and 30, respectively, by bradding or other suitable fastening means. The receptacle 60 is substantially coextensive with the disc half 28 exclusive of the tab portion 34 and extends from the edge 28a counterclockwise to the dotted line 68 when referring to FIGURE 2. Similarly, the receptacle 62 is substantially coextensive with the disc half 30 exclusive of the tab portion 40 and extends from the edge 30a counterclockwise to the dotted line 70 when still referring to FIGURE 2. The fluid receptacles 60 and 62 may conveniently be formed from a single sheet of material die stamped or molded to form the curvature apparent in FIGURE 1. Each of the ends of the two receptacles are tapered upwardly, as best seen in FIGURE 3, at 72 and 74 to complete the fluid receptacles.

Suitable electric switches 76 and 78 are disposed in the receptacles 60 and 62, respectively, and are pivotally connected at 80 and 82, respectively, to C-shaped clamps 84 and 86 which may be connected to the inner edges of the receptacles 60 and 62 by set screws 88 and 90. The mercury switches 76 and 78 may be of conventional construction and housed in airtight glass capsules, but must be buoy-ant in crude oil. When the switches 76 and 78 are resting in the bottoms of the receptacles 60 and 62, as illustrated in FIGURE 1, the switches are open. However, when the receptacles 60 and 62 fill with oil, the switches 76 and 78 are buoyed upwardly to substantially level positions, and the mercury switches will be closed to actuate a shutdown circuit presently to be described.

The shutdown device 25 is preferably secured in position by a pair of straps 92 which are connected by bradding or soldering to the underside of the receptacle 60 and a pair of straps 94-which are similarly connected to the underside of the receptacle 62. The strap-s 92 and 94 extend downwardly and radially inwardly and are connected to any suitable clip which may be secured around the upper end of the tubing string 12 such as half bands 96 and 98 substantially as shown in FIGURE 7. The half band 96 may conveniently be provided with a hook 100 which engages another hook 102 on the half band 98. A bolt 104 may then be passed through projecting ears from the half bands 96 and 98 and a wing nut 106 threaded on the bolt to tightly secure the clip around the upper end of the tubing string 12.

Referring to the circuit diagram of FIGURE 4, a typical circuit which may be used in connection with the shutdown device 25 is indicated generally by the reference numeral 108. Although an electric motor 110 is illustrated as the prime mover for the pumping unit, it is to be understood that any other prime mover, such as an internal combustion engine, could also be shut down by the present invention in the manner hereafter described. A source of electrical power is applied to the motor 110 from the terminals 112 and 114 through a normally closed switchblade 116 and contact 118 of a relay 120. The relay 120 also has another contact 122 and a second normally open Switchblade 124. The primary 126 of a transformer 128 is connected across the power terminals 112 and 114 to continuously supply power to the secondary windings 130. The secondary windings 130 are connected in series with the actuating coil 132 of the relay 120 and with each of the mercury switches 76 and 78, which are connected in parallel with each other, such that upon closure of either mercury switch 76 or 78 the actuating coil 132 of the relay 120 will be actuated. A holding circuit for holding the relay actuating coil 132 energized is comprised of the lead 134, the normally open switchblade 124 of the relay 120, and the lead 136. Therefore, when either switch 76 or 78 is closed by a collection of oil in the receptacle 60 or 62, respectively, the coil 132 of the relay 120 will be actuated. The Switchblade 116 will then move upwardly to open the contact 118 and thereby disable the electric motor 110 of the pumping unit. At the same time, the Switchblade 124 will close against the contact 122 to close the holding circuit and maintain the coil 132 energized, the switchblade 116 open and the motor disabled. The motor 110 will be disabled until such time as the relay 120 is manually reset to open the Switchblade 124 and the holding circuit.

From the above description it will be evident to those skilled in the art that the device 25 may be very economically manufactured. For example, the disc halves 28 and 30 are of identical construction and each may be stamped by the same die from a single sheet to completed form. Similarly, the crescent-shaped receptacles 6t) and 62 are identical and may be stamped from a single sheet by the same die. Or the components may be fabricated from a plastic having high resistance to corrosion. The receptacles may be mated with the respective disc halves and bradded, soldered or otherwise connected around the peripheral flanges. The straps 92 and 94 may then be connected to the receptacles 60 and 62, respectively, by soldering or other suitable means and similarly connected to the half bands 96 and 98. The switches 76 and 78 are connected in place in the receptacles 60 and 62 prior to assembly merely by placing the C-shaped clamps 84 and 86 over the inner edge of the respective receptacles and tightening the screws 88 and 90.

The device 25 may be easily assembled in operative position around the polished rod simply by placing the two half bands 96 and 98 on opposite sides of the upper end of the tubing string, mating the hooks 100' and 102, inserting the bolt 104, and threading the Wing nut 106 loosely on the bolt. The disc halves 28 and 30 may then be conveniently mated and the screws 38 and 42 inserted. When the wing nut 106 is tightened, the device will then be securely connected in place. The split sealing ring 48 may then be placed around the polished rod 18 and secured in place by the arcuate plates 50 and 52. The electrical circuit of FIGURE 4 may then be wired to the switches 76 and 78 and to the prime mover of the pumping unit. Of course, if the prime mover is an electric motor, as will usually be the case, the motor can be disabled merely by breaking the power circuit. If the prime mover is an internal combustion engine, the switch 116 may simply be connected to interrupt the ignition circuit of the engine to disable the pumping unit.

As the polished rod 18 is reciprocated, the ring 48 will wipe crude oil from the polished rod 18 and if in sulficient quantity, the oil will be splashed outwardly into the receptacles 60 and 62. The ring 48 will also make the baflle 26 watertight and the device 25 generally weatherproof. In this connection, it will be noted that the receptacles 60 and 62 are shielded by the bafile member 26 such that rain and other forms of moisture cannot collect in the receptacles and thereby falsely trigger the switches 76 and 78. Any rain or other moisture which may seep downwardly beside the polished rod 18 will tend to pass around the stuffing box 21) and through the narrow annular space between the receptacles 60 and 62.

When the resilient packing material 22 of the stutfing box 20 becomes suificiently worn to slightly leak crude oil by the stuffing box 20, the combined fluid pressure and reciprocating polished rod will quickly erode the packing material until substantial volumes of crude oil will be sprayed generally upwardly with considerable force during each production stroke of the pump. The upwardly spraying crude oil will then strike the battle member 26, and be deflected downwardly into the receptacles 60 and 62. As soon as enough oil has collected in either of the receptacles 60 or 62 to close one of the switches 76 or 78, operation of the pumping unit will be suspended and will remain suspended until the relay 120 is manually reset.

Referring now to FIGURES 5 and 6, another shutdown device constructed in accordance with the present invention is indicated generally by the reference numeral 150. The shut-down device 150 is comprised of a bafiie member, indicated generally by the reference numeral 152, which may also be comprised of two disc halves 154 and 156 having constant radial cross sections substantially as shown in FIGURE 5. The disc halves 154 and 156 are preferably of identical construction. However, the radial edges 154a and 154b of the disc half 154 extend over the radial edges 156a and 15611 of the disc half 156, as shown in dotted outline in FIGURE 6. Screws 158 may then be passed through the overlapping edge portions of the two disc halves 154 and 156 to form the completed circular baffle member 152. The outer corners 1540 of the disc halves 154 and 156 are preferably slightly curved as illustrated in FIGURE 6, such that one of the screws 158 can serve as a pivot point for conveniently assembling the device on a completely assembled pumping unit, as will hereafter be described in greater detail.

A pair of support straps 160 are connected to the outer periphery of the half disc 154 by soldering, bradding or other suitable means and extend downwardly and radially inwardly and are connected to a coupling half band 162. A similar pair of support straps 164 are connected to the outer periphery of the half disc 156 and extend downwardly and radially inwardly and are connected to a second half band 166. The half bands 162 and 166 may be identical to the half bands 96 and 98 illustrated in FIG- URE 7 and may be conveniently connected to the tubing string 12 by suitable fastening means such as the bolt 104 and wing nut 106.

A pair of arcuate impact disc halves 168 and 170 are disposed below and spaced from the disc halves 154 and 156, respectively. The impact disc half 168 is connected to the disc half 154 by three electrical pressure switches 172. The impact disc half 170 is connected to the disc half 156 by three pressure switches 174. The pressure switches 172 and 174 are preferably arranged in the triangle shown in the dotted outlines in FIGURE 6 so as to securely support the arcuate impact disc halves 168 and 170 in stable relationship to the disc halves 154 and 156. The pressure switches 172 and 174 are preferably of the type which require only a very light pressure to actuate, which are well known in the art and which are in extensive use in ofiice buildings, elevators and more expensive homes. Each of the three pressure switches 172 is then wired in parallel in the circuit 108 of FIGURE 4 and replace the switches 76 and 78. Similarly, the pressure switches 174 are wired in parallel with each other and with the pressure switches 172.

Referring now to FIGURE 8, another automatic shutdown device constructed in accordance with the present invention is indicated generally by the reference numeral 180. The shutdown device is substantially identical to the shutdown device 151}, and accordingly all components which are of identical construction are referenced by the same numerals. Thus the two disc halves 154 and 156 are supported by support straps 160 and 164 which are connected to half bands 162 and 166, respectively. However, the arcuate impact discs 168 and 170 are not connected to the disc halves 154 and 156 by the pressure switches 172 and 174. Instead, each of the impact discs 168 and 170 is suspended below the respective disc half by a plurality of springs 182. Then a plurality of pairs of contacts 184 are disposed in normally spaced, circuit opening positions as illustrated in FIGURE 8. One contact of each of the pairs is connected to the res ective impact discs 168 and 170, and the other contact of each of the pairs is connected to the respective half disc 154 and 156 in such a manner that any appreciable movement of the impact discs 168 and 170 in a generally upward direction will close at least one of the pairs of contacts 184 and thereby energize the coil 132 and actuate the relay 120 to disable the motor.

The assembly and operation of the shutdown devices 150 and 180 are substantially identical and accordingly, for convenience of discussion, only the assembly and operation of the shutdown device 150 will now be described in detail, it being understood that the shutdown device 180 can be assembled and operated in the same manner. It will be evident to those skilled in the art that the shutdown device 150 can be very economically manufactured. For example, the disc halves 154 and 156 are identical as are the impact discs 168 and 176, and therefore both sets may be conveniently stamped by single dies. The support straps 160 and 164 are of identical construction and may be connected to the disc halves 154 and 156 and to the half bands 162 and 166 by soldering or any other suitable fastening means. The impact discs 168 and 170 may be connected solely by the pressure sensitive switches 172 and 174 or may be partially suspended by springs as in the case of the shutdown device 180. The device may be very easily assembled around the polished rod 18 merely by inserting one of the screws 158, mating the two hooks of the half bands 162 and 166, pivoting the two disc halves 154 and 156 into position, and then inserting the other screw 158 and the bolt 104 and wing nut 106. The circuitry of FIGURE 4 is then connected to the pressure switches 172 and 174 as previously described and the shutdown device 180 is ready for operation. When the resilient packing material 22 of the st-ufling box 20 wears sufficiently that crude oil is sprayed upwardly against either of the impact discs 168 or 170, the force of impact will close at least one of the pressure switches 172 and 174 and energize the coil 132 to actuate the relay 120 and disable the pumping unit motor 110. The holding circuit will then maintain the motor 110 disabled until the relay 120 is manually reset after the stuffing box 20' has been repaired. It will be noted that the impact discs 168 and 170 are protected from the weather by the baflie member 152 and from direct impact by hail and the like. Even so, the pressure switches 172 and 174 should not be so sensitive as to be actuated by moderate impact blows against the baflle member 152 such as might be caused by hail and other foreign objects.

From the above detailed descriptions, it will be evident that a highly novel shutdown device has been described. The shutdown devices may be easily and economically manufactured and assembled, and are easily removed to permit repair of a faulty stufling box. The shutdown devices are highly reliable and are not subject to false triggering by adverse weather. It will also be noted that the shutdown devices do not interfere in any manner with the normal operation of the pumping unit and may quickly and easily be removed during workover operations. Although several specific and preferred embodiments of the present invention have beendescribed in detail, it.is to be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

What is claimed is: 1. A shutdown device for automatically disabling a pumping unit having a prime mover which drives a rod member extending through a stuffing box, the shutdown device comprising:

bafl'le means adapted to be disposed substantially around the rod member adjacent the stufling box;

impact plate means connected to the baffle means and adapted to be disposed adjacent the stufling box so as to be impacted by fluid sprayed from the stufling box;

switch means disposed between the baffle means and the impact plate means adapted to be actuated upon impact of fluid against the impact plate means; and

circuit means adapted to be connected to the switch means and to the prime mover for disabling the prime mover upon actuation of the switch means,

whereby upon leakage of fluid through the stufling box the pumping unit will be shut down.

2. A shutdown device for automatically disabling a pumping unit having a prime mover connected to drive a vertically disposed rod which extends downwardly through a stutfing box, the shutdown device comprising:

a pair of disc half members adapted to be disposed around the rod above the stuffing box and interconnected;

an impact plate member disposed below each of the disc half members and adapted to be disposed above the stuffing box;

switch means connected to one of the members for actuation upon movement of either of the impact plate members toward the respective disc half members; and,

circuit means connected to the switch means and adapted to be connected to the prime mover for disabling the prime mover upon actuation of the switch means,

whereby when fluid is sprayed upwardly from the stuffing box, the fluid will impact the impact plate members and actuate the switch means thereby disabling the pumping unit.

3. A shutdown device for automatically disabling a pumping unit as defined in claim 2 wherein:

the switch means is a plurality of pressure sensitive switches which interconnect the impact plate members and the respective disc half members.

4. A shutdown device for automatically disabling a pumping unit as defined in claim 2 wherein:

the impact plate members are connected to the respective disc half members by spring means; and,

each of the switch means is comprised of a pair of normally spaced contacts, one of the contacts being connected to the impact plate,

the switch means is a plurality of pairs of normally spaced contacts, one of each pair of contacts being connected to one of the impact plate members and the other connected to the respective disc half member,

whereby when fluid is sprayed upwardly from the stuffing box, the fluid will impact one of the impact plate members and move the impact plate member upwardly to close at least one of the pairs of contacts and thereby disable the pumping unit.

References Cited by the Examiner UNITED STATES PATENTS 1,768,918 7/1930 Meyer 20061.04 X

BERNARD A. GILHEANY, Primary Examiner.

G. MAIER, Assistant Examiner. 

1. A SHUTDOWN DEVICE FOR AUTOMATICALLY DISABLING A PUMPING UNIT HAVING PRIME MOVER WHICH DRIVES A ROD MEMBER EXTENDING THROUGH A STUFFING BOX, THE SHUTDOWN DEVICE COMPRISING: BAFFLE MEANS ADAPTED TO BE DISPOSED SUBSTANTIALLY AROUND THE ROD ADJACENT THE STUFFING BOX; IMPACT PLATE MEANS CONNECTED TO THE BAFFLE MEANS AND ADAPTED TO BE DISPOSED ADJACENT THE STUFFING BOX SO AS TO BE IMPACTED BY FLUID SPRAYED FROM THE STUFFING BOX; SWITCH MEANS DISPOSED BETWEEN THE BAFFLE MEANS AND THE IMPACT PLATE MEANS ADAPTED TO BE ACTUATED UPON IMPACT OF FLUID AGAINST THE IMPACT PLATE MEANS; AND CIRCUIT MEANS ADAPTED TO BE CONNECTED TO THE SWITCH MEANS AND TO THE PRIME MOVER FOR DISABLING THE PRIME MOVER UPON ACTUATION OF THE SWITCH MEANS, WHEREBY UPON LEAKAGE OF FLUID THROUGH THE STUFFING BOX THE PUMPING UNIT WILL BE SHUT DOWN. 